As the ink-jet printing field develops, improvements in printing characteristics such as edge acuity, optical density, substrate adherence, dry time, resolution, durability, and waterfastness continue to be explored. At the same time, while trying to improve upon these characteristics, fluids of the ink-jet system should also provide long term storage compositional stability and long term reliability without equipment corrosion or nozzle clogging. Though the above lists of characteristics provide a worthy goal, there are difficulties associated with satisfying all of the above characteristics. Often, the inclusion of an ink component meant to satisfy one of the above characteristics can prevent another characteristic from being met. Thus, most commercial inks for use in ink-jet printers represent a compromise in an attempt to achieve at least an adequate response in meeting all of the above listed objectives.
Various substances have been used to formulate ink-jet inks and other recording solutions in an attempt to meet the above objectives. Some of these substances have been included are pigments and/or dyes to provide color to the image, water and/or water-soluble organic solvents to provide a liquid composition that functions properly within ink-jet equipment, surfactants of various ionic character to provide decreased surface tension at various liquid interfaces, dispersants for enhancing solubility characteristics, and various other solution characteristic modifiers such as viscosity modifiers, pH adjustors, antiseptics, antioxidants, chelating agents, biocides, and the like.
Printing media has also been modified to utilize a variety of substances, including various binding materials to improve recording parameters. These binding materials can include inorganic porous coatings, such as silica and alumina, or swellable organic coatings, such as gelatins and other similar compositions. These materials can be coated on a paper or other substrate to provide improvement in image quality when an ink-jet ink is printed thereon, as is generally known in the art.
A development in the ink-jet printing area has been the use of ink-jet inks concurrent with another solution in a two pen ink system. Such other solutions can be formulated to operate with the ink to provide more durable images and/or enhancement in image color and clarity.
Many pigment-based ink-jet systems can have relatively slow drying times due in part to the vehicle components typically used to disperse the pigments and maintain customary long term reliability and durability during use and storage. Another reason for the lack of optimal performance can be related to the presence of certain binders often present in these pigment-based ink-jet ink compositions. Many binders known to be used can improve permanence greatly, but can actually slow the drying process.
As a result of the state of the art, it would be desirable to provide ink-jet systems, methods, and ink-jet images printed on a porous media substrate that can be prepared with reduced drying time, while maintaining adequate print durability after printing, as well as long term storage stability while the printing fluids are housed in the ink-jet pen.